In order to reduce the running noise of a tire provided with a tread comprising a tread pattern, it is known to place in sequence, in the longitudinal direction of this tread, a succession of motifs derived from one and the same elementary motif, except for a scale ratio, so as to distribute the acoustic energy as homogeneously as possible over a wider range of frequencies.
It is also known, for example from EP 114 594, to construct a tread pattern comprising side by side at least two annular distributions each formed of a plurality of repeating motifs, the number of motifs of an annular distribution located on one half of the tread being of between 5% and 50% of the number of motifs of another annular distribution located on the other half of the same tread.
Although on average it makes it possible to improve the subjective perception of the occupants of a vehicle during travel, the latter construction technique in a certain number of cases leads to relatively poor-quality results in terms of noise inside the vehicle. It was therefore necessary to determine complementary rules for optimization of the construction of a tire tread pattern and in particular one for a passenger-vehicle tire.
Furthermore, documents EP 524 568 and U.S. Pat. No. 2,808,867 both propose tread patterns comprising a plurality of distributions without however laying down precise construction rules for the different distributions which make it possible to optimize the performance of the tread patterns.
The invention described here proposes providing a method for constructing a tire tread pattern having at least two different distributions with the aim of reducing the acoustic discomfort felt inside a vehicle.